Vehicle headlamp with daytime running light

ABSTRACT

A vehicle headlamp. The headlamp comprises a light source and a reflector to direct light received from the light source out of the headlamp. A movable shade is positionable to control the light received by the reflector. A shade driver is coupled to the movable shade to position the shade. A first shade position configures the headlamp for high beam lighting. A second shade position configures the headlamp for low beam lighting. A third shade position configures the headlamp for daytime running lights.

This application is a continuation of U.S. patent application Ser. No.11/361,555, filed Feb. 24, 2006.

FIELD

The present invention relates to vehicle headlamps, in particular avehicle headlamp capable of varying the light distribution of areflector assembly by adjusting the position of a movable shade inrelation to a lamp.

BACKGROUND

Vehicles commonly have headlamps that provide low and high beam lightingfor driving at night. High beam lighting provides a substantial amountof light aimed so as to enable the driver to see greater distances ondark roads, while low beam lighting provides a lesser amount of lightaimed closer to the vehicle for driving on lighted streets or to preventdazzling drivers of oncoming vehicles. Separate incandescent and/orhalogen lamps may be utilized for low and high beam headlamps.Alternatively, a single lamp may have a plurality of selectablefilaments for high and low beam operation, or a high beam lamp may bedimmed for low beam operation.

Vehicle designers are increasingly turning to high intensity discharge(“HID”) lamps for use in headlamp systems due to their high efficiencyin comparison to incandescent and halogen lamps. A typicalcharacteristic of HID lamps is that they must be operated at a generallyfixed power level for proper operation. This inflexibility makes dimmingof an HID high beam headlamp for low beam operation impractical. Toavoid the complexity and expense of utilizing two HID systems to coverboth high beam and low beam operation, vehicle designers haveincorporated into headlamp assemblies various types of movable shadesproximate a single HID lamp. The shades are typically moved topredetermined positions proximate the lamp for low beam operation,partially shielding and/or redirecting light emitted from the lamp.Accordingly, only a portion of the total amount of light emitted by thelamp reaches a reflector to be directed out of the headlamp. When highbeam operation is desired, the shade is moved away from the HID lamp,allowing a greater portion of the light emitted by the lamp to reach thereflector and be directed out of the headlamp.

As a safety enhancement many vehicles now include daytime running lights(“DRL”) in addition to low and high beam headlamps. As the term implies,DRL are normally operated in substantially daylight conditions. Avehicle equipped with DRL is more likely to be noticed by other drivers,thereby reducing the probability of a collision with the vehicle.

Daytime running lights that use incandescent or halogen lamps as a lightsource are typically formed from the vehicle's low or high beamheadlamps. For DRL operation with high beam headlamps, the headlamps areoperated at a reduced intensity. Alternatively, low beam headlamps maybe operated at either full or reduced power for DRL operation. Suchsystems are designed to automatically function as DRL when the vehicleis started and to be overridden when regular high or low beam headlampsare activated.

DRL presents a challenge for HID-based vehicle lighting systems, sinceHID lamps must be operated at a relatively fixed power level and are noteasily dimmed, as discussed above. This limitation often drives the useof a separate DRL unit, adding cost and complexity to the vehicle. Thus,there is a need for a way to avoid the expense and complexity of aseparate DRL system for vehicles having headlamps that use HID lamps asa light source.

SUMMARY

The present invention utilizes a movable shade that can be positioned atpredetermined locations in relation to an HID lamp to control thelighting pattern and intensity of an HID headlamp for low beam and highbeam operation. In addition, the movable shade can be positioned at athird predetermined location such that light emitted by the HID lampmeets vehicle requirements for DRL operation. Thus, the HID lamp can beoperated a fixed power level while the light output of the headlamp canbe electro-mechanically controlled to meet illumination needs for thevehicle for low beam, high beam and DRL operational modes.

An aspect of the present invention is a vehicle headlamp. The headlampcomprises a light source and a reflector to direct light received fromthe light source out of the headlamp. A movable shade is positionable tocontrol the light received by the reflector. A shade driver is coupledto the movable shade to position the shade. A first shade positionconfigures the headlamp for high beam lighting. A second shade positionconfigures the headlamp for low beam lighting. A third shade positionconfigures the headlamp for daytime running lights.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the inventive embodiments will become apparent tothose skilled in the art to which the embodiments relate from readingthe specification and claims with reference to the accompanyingdrawings, in which:

FIG. 1 is a sectional side elevation of a vehicle headlamp according toan embodiment of the present invention;

FIG. 2A depicts low and high beam positions of a movable shade inrelation to a discharge lamp for a headlamp according to an embodimentof the present invention;

FIG. 2B depicts low beam and DRL positions of the movable shade of FIG.2A in relation to the discharge lamp;

FIG. 3A illustrates example lighting patterns for light incident on areflecting surface for low and high beams of a headlamp according to anembodiment of the present invention;

FIG. 3B illustrates example lighting patterns for light incident on areflecting surface for DRL and high beams of a headlamp according to anembodiment of the present invention;

FIG. 4 is a block diagram showing the general arrangement of a system tocontrol the position of a movable shade of a vehicle headlamp, accordingto an embodiment of the present invention;

FIG. 5 is a block diagram showing the general arrangement of a system tocontrol the position of a movable shade of a vehicle headlamp, accordingto an alternate embodiment of the present invention;

FIG. 6 is a block diagram depicting the general arrangement of a systemto control the position of a movable shade of a vehicle headlamp,according to another alternate embodiment of the present invention; and

FIG. 7 is a block diagram showing an alternate arrangement of the systemof FIG. 6, according to yet another alternate embodiment of the presentinvention.

DETAILED DESCRIPTION

In the discussion that follows, like reference numerals are used toindicate like elements and structures in the various figures.

FIG. 1 is a sectional side elevation of a vehicle headlamp 10 accordingto an embodiment of the present invention. The headlamp 10 according tothis embodiment includes a reflector assembly 12 mounted in a lampchamber 13 that is generally defined by a transparent cover 14 and ahousing 16. Reflector assembly 12 includes a discharge lamp 18, areflector 20, a movable shade 22, a shade driver 24 and a lamp supportbase 26.

Cover 14 is generally transparent and serves to protect reflectorassembly 12 from exposure to the elements. Cover 14 is a conventionalcover made from any suitable conventional materials, such as glass andplastic. In some embodiments cover 14 may also include various grooves,fillets, contours and shapes optically designed to at least partiallyshape the distribution of light emitted from headlamp 10.

Light distribution of headlamp 10 is primarily controlled by reflectorassembly 12. Reflector 20 has a reflecting surface 28 for directinglight received from discharge lamp 18 in a generally forward direction“A” so that a beam is formed and emitted with a prescribed lightdistribution pattern that is shaped by diffusing and/or deflecting thelight incident on the reflecting surface. Reflector 20 may be anyconventional type of optical reflector, such as an elliptical orparabolic reflector.

Lamp 18 provides a light source for headlamp 10. Lamp 18 may be anyconventional type of discharge lamp including, as a non-limitingexample, a high pressure metal vapor discharge lamp such as a metalhalide HID lamp.

Lamp 18 is fixedly supported in relation to reflector 20 by lamp supportbase 26 so that a light-emitting portion 30 of the lamp is positionedgenerally at an optical focal point of reflector 20. Lamp support base26 may be made of any suitable material, such as metal, plastic andceramic, and extends through an opening 32 of reflector 20.

Movable shade 22 comprises a shade body 34 and a shade leg 36. Shadebody 34 is preferably opaque and generally cylindrical in shape with anopen end oriented toward lamp 18 and an opposing, closed end. Shade body34 may be made from any suitable material, such as metal, plastic,coated glass and ceramics. The material selected for shade body 34 ispreferably capable of withstanding heat generated by lamp 18, along withother environmental considerations for headlamp 10. Shade body 34 mayoptionally have a polished, absorptive or reflective inner and/or outersurface. In various embodiments shade body 34 may be other geometricshapes, such as elliptical, hexagonal, octagonal and rectangular shapes.Cut-outs may also be added to shade body 34 as desired, to further shapethe lighting pattern or control the lighting output of headlamp 10.

Shade leg 36 extends between shade body 34 and shade driver 24. Shadeleg 36 may extend from the closed end of shade body 34 or from asidewall of the shade body. Shade leg 36 may be a separate componentthat is attached to shade body 34, or may be formed as an integral partof the shade body. The shape and dimensions of shade leg 36 are notcritical and may vary as needed to accommodate the arrangement of othercomponents of headlight 10.

Shade driver 24 comprises a drive member 38 actuable by an electricmotor 40. Motor 40, when powered, causes drive member 38 to movebidirectionally and generally linearly along an axis “B” such that shadebody 34 shields more or less of the light emitted by lamp 18 fromreaching reflective surface 28. Motor 40 may be any conventional type ofmotor including, but not limited to, a permanent magnet motor, abrushless DC motor and a stepper motor. Motor 40 may optionally includea dynamic and/or mechanical brake 42 to stop the motor and/or keep itsshaft 44 from rotating when the motor is not operating. Motor 40 mayfurther include a gear reduction 46 to provide an output displacement,velocity and torque that is compatible with drive member 38 to moveshade 22.

Drive member 38 converts rotary motion from motor 40 to linear motion tomove movable shade 22 toward or away from lamp 18 in accordance with theselected position for the shade, as detailed above. Drive member 38 maybe any conventional type of rotary-to-linear motion converter including,without limitation, a ball screw, lead screw, belt drive, and arack-and-pinion. In some embodiments drive member 38 may be arotary-to-oscillatory converter, such as a four-bar linkage mechanism.In other embodiments motor 40 and drive member 38 may be replaced by alinear motor-actuator. Drive member 38 may further comprise gearing toreduce the speed of rotational motive force provided by motor 40 and/oramplify the amount of motive force delivered by the motor.

With reference now to FIG. 2A, movable shade 22 can be positioned at ahigh-beam forming position, shown in outline at discrete position “C,”and a low-beam forming position, shown at discrete position “D.” Shadebody 34 partially shields lamp 18 when it is positioned at the low-beamposition “D,” thereby reducing the amount of light presented toreflecting surface 28. Shade body 34 does not substantially shield lamp18 when positioned at the high-beam position “C,” thereby allowing agreater amount of the light emitted by the lamp to reach reflectingsurface 18.

With reference to FIG. 2B, movable shade 22 can be further moved to athird, discrete DRL position, shown in outline as position “E.” Atposition “E,” shade body 34 shields lamp 18 to an even greater degreethan at low beam forming position “D,” thereby allowing a lesser amountof light sufficient for DRL operation to reach reflecting surface 28.

The effect of the position of movable shade 22 upon light emitted byvehicle headlamp 10 is observed by additional reference to FIG. 3A. Inparticular, when at the low beam forming position “D” shown in FIG. 2A,movable shade 22 surroundably shields at least a portion of lamp 18 toobstruct a portion of light emitted from the lamp. Movable shade 22accordingly prevents the obstructed light from reaching a peripheralregion “G(H)” of the reflecting surface 28, allowing the unobstructedportion of the light emitted by lamp 18 to be directly incident only ona central region “G(L)” thereof such that only a predetermined amount oflight required to emit a low beam is incident on the reflecting surface28. Conversely, when at the high-beam forming position “C” of FIG. 2Amovable shade 22 allows the light to be incident on substantially theentire region of reflecting surface 28 (i.e., both regions G(H) andG(L)) so as to ensure a sufficient amount of light to emit a high beam.

With reference to FIG. 3B, when at the daytime running light position“E” of FIG. 2B, movable shade 22 surroundably shields at least a portionof lamp 18 to obstruct a portion of the light emitted from the lamp andprevents the obstructed light from reaching the peripheral region G(P)of the reflecting surface 28. The unobstructed portion of the lightemitted by lamp 18 is directly incident only on a central region G(DRL)thereof such that only a predetermined amount of light required to emita daytime running light is incident on reflecting surface 28.

With reference now to FIG. 4, in accordance with an embodiment of thepresent invention movable shade 22 is selectively actuated to theaforementioned low beam, high beam and DRL positions by shade driver 24in cooperation with a motor driver 46, a controller 48, a positionfeedback element 50 and a mode control 52.

Motor driver 46 provides electrical power suitable for operating motor40 and may be tailored to the requirements of the type of motor selectedfor a particular configuration of the present invention. For example,electromechanical and solid state relays and solid state devices such asbipolar and field effect transistors may be used to selectively supplypower to motor 40 for either unidirectional or bidirectional rotation ofan output shaft (not shown) of the motor. In addition, motor driver 46may be configured to provide commutation to motors that require externalcommutation, such as brushless DC and stepper motors. Motor drivers andcommutators for the various types and winding configurations of motorsare well-known in the art. Accordingly, construction details of motordriver 46 are left to the artisan.

Controller 48 receives command information corresponding to apredetermined selected position (i.e., positions “C,” “D,” “E” of FIGS.2A and 2B) for movable shade 22 from mode control 52 and determines theactual position of the movable shade from information provided byfeedback element 50. If the position of movable shade 22 does not matchthe position commanded by mode control 52, controller 48 actuates motordriver 46 to operate motor 40 in a predetermined manner until feedbackelement 50 indicates to the controller that the movable shade has movedto the selected position.

Controller 48 may further monitor for various fault conditions andresolve them in a predetermined manner. For example, controller 48 maymonitor for a locked motor rotor, over-temperature or short-circuitconditions in motor 40, over-temperature and over-current conditions inmotor driver 46, illegal or invalid mode control 52 inputs, and invalidposition information from feedback element 50. Example fault resolutionresponses for controller 48 include, without limitation, selectablyremoving power from faulty components of headlight 10, rerouting poweramong components of the headlight, calculating the current and/orcommanded position of movable shade 22 from a last-known position, andswitching from faulty components to alternate components. Controller 48may further include fault resolution wherein movable shade 22 ispositioned at a predetermined position under certain fault conditions,thus allowing the vehicle to be driven pending resolution of the fault.A secondary position sensing arrangement and/or a mechanical stop 54(FIG. 4) may optionally be included, thus allowing movable shade 22 tobe positioned at the predetermined position even in the event of afailure of feedback element 50.

Controller 48 may be implemented in any conventional form of analog ordigital closed-loop servo controller having operational aspectsincluding, but not limited to, force, velocity and directional controlsfor motor 40. Controller 48 may further include a predetermined set oflogical instructions, such as a computer program, to define the variousoperational aspects of the controller.

Position feedback element 50 provides information to controller 48relating to the position of movable shade 22. Feedback element 50 may beany conventional type of feedback element in the art that is compatiblewith the architecture chosen for controller 48. For example, feedbackelement 50 may be an absolute or relative position encoder. In otherembodiments feedback element 50 may be an arrangement ofelectromechanical or solid state limit switches or proximity-sensingelements located at predetermined positions relative to movable shade22. In some embodiments utilizing a stepper or brushless DC motor alimit switch or proximity sensor at a known or calibrated position ofmovable shade 22 may serve as an index point for a predetermined set ofinstructions used by controller 48 to count the number of commutationpulses required to reach a predetermined position of the movable shade.In addition to position information, feedback element 50 may providecontroller 48 with information relating to the velocity of movable shade22 when it is moving. The aforementioned encoders, switches andproximity-sensing elements for position feedback are well-known in theart. Accordingly, details of these devices are not further elaboratedupon herein.

Mode control 52 provides controller 48 with information relating to theselected position of movable shade 22, i.e. whether the shade is to bein high beam position “C” or low beam position “D” of FIG. 2A, or theDRL position “E” of FIG. 2B. In practice, mode control 52 may beincorporated as an element of a system that controls various operationalaspects of the vehicle's headlamps. For example, mode control 52commands may be generated variously by one or more of a driver'scontrol, ambient lighting sensors and automatic headlamp dimmingcontrols (not shown).

With reference now to FIGS. 1-4 in combination, in operation of headlamp10 the lamp 18 is powered at a predetermined optimum power level suchthat it emits substantially the same amount of light for low beam, highbeam and DRL modes of the headlamp. If high beam operation of headlamp10 is desired, mode control 52 provides a command signal to controller48 representing high beam mode. In response, controller 48 usesinformation from feedback element 50 to determine whether movable shade22 is in the predetermined position “C” for high beam operation. Ifmovable shade 22 is in the prescribed position for high beam operation,controller 48 takes no further action. However, if movable shade is notin the prescribed position for high beam operation, controller 48actuates motor driver 46, which in turn supplies power to operate motor40. Motor 40 provides rotary motive power to drive member 38, which inturn acts to generally linearly move movable shade 22 in the directionrequired to achieve the commanded mode. As movable shade 22 moves,controller 48 periodically or continuously monitors the position of themovable shade using information from feedback element 50. Whencontroller 48 determines that the predetermined position of movableshade 22 for high beam operation of headlamp 10 has been reached, thecontroller de-actuates motor driver 46, causing power to be removed frommotor 40 and causing the movable shade to come to rest at thepredetermined position. Motor 40, drive member 38, motor driver 46,controller 48, feedback element 50 and mode control 52 all function in alikewise manner to position movable shade 22 for low beam and DRL modesof operation of headlamp 10 at positions “D” and “E,” respectively.

FIG. 5 depicts the general arrangement of a shade driver 124 comprisinga drive member 138 and a pair of motors 140 a, 140 b (generally termed“motors 140”) to control the position of a movable shade 22 of a vehicleheadlamp according to an alternate embodiment of the present invention.Movable shade 22 is actuated by motor 140 a and/or 140 b, each motorbeing coupled to the shade by a common drive member 138. Each motor 140a, 140 b may be configured to operate such that a corresponding outputshaft 142 a, 142 b respectively (generally termed “output shafts 142”),rotates between two predetermined limit positions or stops 154 (FIG. 5).

In operation, one of motors 140 is actuated, causing its correspondingoutput shaft 142 to rotate clockwise or counter-clockwise to one of twolimit positions, in turn causing drive member 138 to reposition shade 22at a corresponding predetermined position, the displacement of the shadebeing determined by the angular rotation of the actuated motor's outputshaft and the mechanical characteristics of drive member 138. The outputshaft 142 of the unactuated motor rotates freely, allowing the outputshaft to be driven by common drive member 138. A plurality of positionsfor shade 22 may be selected by mode control 52, depending upon suchfactors as actuation of only one of motors 140, actuation of one ofmotors 140 and then the other motor, the order of actuation of motors140, and the predetermined angular displacement limits for each ofoutput shafts 142 a, 142 b, among others.

Motors 140 may be any conventional type of motor including, but notlimited to, a permanent magnet motor, a brushless DC motor, a linearactuator and a stepper motor. Motors 140 may optionally include adynamic and/or mechanical brake to stop the motor and/or keep it fromrotating when it is not actuated. Motors 140 may further include a gearreduction to provide an output shaft displacement, velocity and torquethat is compatible with drive member 138 to move shade 22. For example,motors 140 may be DC gearmotors having integral limit switches (notshown) such that output shafts 142 move to a counter-clockwise positionwhen a voltage having a first polarity is applied to the motor.Conversely, output shafts 142 may move to a clockwise limit positionwhen a voltage having opposite polarity is applied to motors 140. Inanother example, motors 140 may be programmable stepper motors underdirectional and rotational control of a controller 148 wherein outputshafts 142 rotate predetermined number of angular displacement stepswith reference to an index or stop, providing for fixed limit positionsin the clockwise and counter-clockwise directions of the output shafts.

Drive member 138 may be any conventional type of rotary-to-linear motionconverter including, without limitation, a ball screw, lead screw, beltdrive, and a rack-and-pinion. In some embodiments drive member 138 maybe a rotary-to-oscillatory converter, such as a four-bar linkagemechanism. Drive member 138 may further comprise gearing to reduce thespeed of rotational motive force provided by motors 140 and/or amplifythe amount of motive force delivered by the motors. In other embodimentsmotors 140 and drive member 138 may be replaced by a linearmotor-actuator.

In addition to having the previously-discussed aspects of controller 48,controller 148 may include position-tracking capability. Theposition-tracking capability of controller 148 can be configured tostore data relating to an initial known calibration or index position ofshade 22 and also store data relating to subsequent actuations of eachof motors 140. This stored information can then be utilized bycontroller 148 to compute and track the current position of shade 22 todetermine the required actuation of motors 140 to move shade 22 to adesired position in response to a command input received from modecontrol 52. Alternatively, controller 148 may receive positioninformation from a feedback element 50 (see FIG. 4), as previouslydiscussed, to move shade 22 to a desired position using one or both ofmotors 140.

FIG. 6 shows the general arrangement of a shade driver 224 comprising apair of drive members 238 a, 238 b (generally termed “drive members238”) and a pair of motors 240 a, 240 b (generally termed “motors 240”)to control the position of a plurality of movable shades of a vehicleheadlamp, according to another alternate embodiment of the presentinvention. A first movable shade 222 a is actuated by a motor 240 athrough an intermediate drive member 238 a. A second movable shade 222 bis likewise actuated by a motor 240 b through an intermediate drivemember 238 b. A shade body 234 b is configured to movably fit within ashade body 234 a.

Motors 240 may be any type of motor suitable for use with headlightsystem 10, such as those discussed above for motors 40 and 140.Likewise, drive members 238 may be any type of drive mechanism suitablefor use with headlight system 10, such as those discussed above fordrive members 38, 138. Each motor 240 may optionally be configured toactuate a corresponding drive member 238 between two predetermined limitpositions or stops 254 (FIG. 6) in the manner previously described formotors 140.

Shades 222 a, 222 b (generally termed “shades 222”) may be configuredsimilarly to shade 22, with shade body 234 b being generally coaxial tofit within shade body 234 a. Shade body 234 b is also independentlypositionable with respect to shade body 234 a. In one embodiment shade222 a may include a longitudinal slot 235 through which a shade leg 236b of drive member 238 b extends, as shown in FIG. 6. Alternatively, anaperture 237 located at a closed end 239 of shade 222 a can be providedto allow shade leg 236 b and/or drive member 238 b access to inner shade222 b, as shown generally in FIG. 7.

With reference to FIGS. 6 and 7, controller 248 may include the featuresof either or both of controllers 48, 148 discussed above. Theposition-tracking capability of controller 248 can be configured tostore data relating to an initial known calibration or index position ofshades 222 and also store data relating to subsequent actuations of eachof motors 240. This stored information can then be utilized bycontroller 248 to compute the required actuation of motors 240 tosatisfy a command input received from mode control 52 to move either orboth of shades 222 to a desired position. Alternatively, controller 248may receive position information from a feedback element 50 aspreviously discussed (see FIG. 4), to move each of shades 222 a, 222 bto desired positions using corresponding drive members 238 a, 238 b andmotors 240 a, 240 b.

In operation, motor 240 a may be actuated independently of motor 240 b,causing drive member 238 a to move shade 222 a to one of twopredetermined limit positions, the displacement of the shade beingdetermined by the angular rotation of the motor and the mechanicalcharacteristics of drive member 238 a. Motor 240 b may likewise beactuated independently of motor 240 b, causing drive member 238 b tomove shade 222 b to one of two predetermined limit positions, thedisplacement of the shade being determined by the angular rotation ofthe motor and the mechanical characteristics of drive member 238 b. Inthis embodiment a plurality of shading levels for lamp 18 may beselected by mode control 52, depending upon such factors as actuation ofonly one of motors 240, actuation of one of motors 240 and then theother motor, the order of actuation of motors 240, and the predeterminedangular displacement of drive members 238, among others.

While this invention has been shown and described with respect toseveral detailed embodiments thereof, it will be understood by thoseskilled in the art that changes in form and detail thereof may be madewithout departing from the scope of the claims of the invention.

1. A vehicle headlamp, comprising: a light source; a reflector to directlight received from the light source out of the headlamp; a movableshade configured to surroundably shield the light source, the shadebeing linearly positionable to a plurality of discrete positions toadjustably limit the amount of light received by the reflector directlyfrom the light source; and a shade driver coupled to the movable shadeto position the shade, wherein: a first discrete shade positionconfigures the headlamp for high beam lighting, a second discrete shadeposition configures the headlamp for low beam lighting, and a thirddiscrete shade position configures the headlamp for daytime runninglights.
 2. The vehicle headlamp of claim 1, further comprising acontroller coupled to the shade driver through a motor driver.
 3. Thevehicle headlamp of claim 2 wherein the controller is one of an analogand a digital servo controller.
 4. The vehicle headlamp of claim 2,further comprising a feedback element coupled to the movable shade andthe controller.
 5. The vehicle headlamp of claim 2 wherein thecontroller further includes position-tracking capability.
 6. The vehicleheadlamp of claim 2 wherein the controller further monitors for faultconditions and resolves said fault conditions.
 7. The vehicle headlampof claim 2, further comprising a mode control coupled to the controller.8. The vehicle headlamp of claim 1 wherein the shade driver furthercomprises a linear actuator.
 9. The vehicle headlamp of claim 1 whereinthe shade driver further comprises a drive member coupled to the movableshade, and a motor coupled to the drive member.
 10. The vehicle headlampof claim 9 wherein the drive member is one of a ball screw, lead screw,belt drive, rack-and-pinion and four-bar linkage mechanism.
 11. Thevehicle headlamp of claim 9 wherein the motor is one of a permanentmagnet motor, a brushless DC motor and a stepper motor.
 12. The vehicleheadlamp of claim 9, further comprising at least one stop to positionthe movable shade.
 13. The vehicle headlamp of claim 9 wherein the motorfurther includes at least one of a gear reduction and a brake.
 14. Avehicle headlamp, comprising: a light source; a reflector to directlight received from the light source out of the headlamp; a movableshade configured to surroundably shield the light source, the shadebeing linearly positionable to a plurality of predetermined discretepositions to adjustably limit the amount of light received by thereflector directly from the light source; and a shade driver to positionthe movable shade, the shade driver comprising a drive member that iscoupled to the movable shade and is further commonly coupled to a pairof motors, wherein: a first discrete shade position configures theheadlamp for high beam lighting, a second discrete shade positionconfigures the headlamp for low beam lighting, and a third discreteshade position configures the headlamp for daytime running lights. 15.The vehicle headlamp of claim 14, further comprising at least one stopto position the movable shade.
 16. The vehicle headlamp of claim 14wherein the drive member is one of a ball screw, lead screw, belt drive,rack-and-pinion and four-bar linkage mechanism.
 17. The vehicle headlampof claim 14, further comprising a controller having position-trackingcapability, said controller being coupled to the shade driver through amotor driver. 18-23. (canceled)
 24. A method for controlling the lightemitted by a vehicle headlamp, comprising the steps of: providing alight source; positioning a reflector proximate the light source todirect light emitted by the light source out of the headlamp; linearlypositioning proximate the light source a movable shade configured tosurroundably shield the light source; and adjusting the movable shade toone of a plurality of predetermined discrete positions to limit theamount of light received by the reflector directly from the lightsource, wherein: a first discrete shade adjustment position configuresthe headlamp for high beam lighting, a second discrete shade adjustmentposition configures the headlamp for low beam lighting, and a thirddiscrete shade adjustment position configures the headlamp for daytimerunning lights.